Igniter coil manufacture



1939- H w. BILGER ET AL IGNITER COIL MANUFACTURE Filed Aug. 20, 1937INVENTORS Patented May 2, 1939 rom'rnn con. MANUFACTURE Henry w. Bilgerand Karl 'r. Kessel, Meriden,

Conn., assignors to The Cuno Engineering Corporation, Meriden', ml" acorporation of Connecticut "Application August 20, 1937, Serial No.160,046

. v 6 Claims. (Cl. 29-1555) Our invention relates to a method and meansfor forming a resistance coil for cigar lighters and the like andespecially coils of flat wire or ribbon wound in spiral form.

These coils "are commonly formed by winding the ribbon on a handoperated, hand controlled or automatic machine in which the wire is fedonto a mandrel of proper diameter to form the central turn. The ribbonis then wound coil upon 10 coil to form a spiral with all of the turnssubstantially in one plane. Qne disadvantage of this method is that itrequires wire of a definite temper so that the coil is wound andreleased the normal spring of the wire is suficient to cause 15 theturns to space themselves from one another so as to prevent shortcircuiting. Another disadvantage of this method is that when the wirehas sufiicient temper to properly space itself when released afterwinding and the twoends of the 20 coil are fixed to rigid-conductingmembers in the assembled heating unit, the coils when heated,

as in use, tend to shift somewhat and they leecome annealed intoirregular relation with respect to one another. Some of the coils aretoo too far apart.

We have sought to provide a method of manufacture which will obviatethese difdculties and produce a coil the turns of which will beuniformly 3 spaced.

For this purpose we provide an arbor, the end of which is approximatelyconical but provided with steps arrangedin the form of a combined helixand spiral. We use a dead soft or an- 35 nealed wire or ribbon. Sincethis has no itendency to spring it takes and retains the size andspacing given it on the arbor and no shifting of coils takes place whenheated in use. As these coils are usually flat or only slightly convex,

40 we bring the helico spiral coil into the flat or substantially fiatform by compressing it between dies. The-resulting coil is asubstantially fiat spiral of regularity and uniformity and its form isheld I indefinitely in use.

45 Fig. 1 is an enlarged side view of the arbor showing acoil in sectionformed upon it.

Fig. 2 is an end view 01 the arbor.

Fig. 3 is v a fragmentary section on a much enclose and tend to shortcircuit and others are in the terminal or contact cup of an igniterelement. v

Fig. 7 is a perspective view of "a fragment of the. 'end of the ribbonto form the central part of the coik. The mandrel or arbor 8 is formedof suitable metal and adapted to be rotated in a suitable type latheetc. The end 9 of the arbor is in general conical and provided with aseries of steps increasing in'diameter spirally and progressing ax- 10ially at the same time at a uniform pitch.

The ribbon in has its tip ll bent overat an angle to fit in the slot E2in the extreme end of the arbor. The central part it of the arbor may beformed separately from a rod and insorted and held adjustable in thebody of the arbor. At each turn of the steps the radiusincreases by theamount it enough more than the thickness of the ribbon to allow for thespace required between adjacent turns of the ribbon in the -finished.coil. The axial width id of each step is less than the Width of theribbon so that each turn overlaps the preceding turn as shown in Fig. 3.This makes it mucheasier to flatten or collapse the coil to the positionof Figs. 4 and 6.

The ribbon or fiat wire is made dead soft or highly annealed so thatwhen the arbor is rotated the ribbon will lie smoothly upon the helicovspiral steps. As the wire has no resiliency or tendency to spring, ittakes and retains its shape with the size and spacing of the turnsdetermined by steps on the arbor on which it is wound.

If the coil is to be made more shallow axially it is a simple matter toshape it between dies to the slightly convex or concave form shown inFig. 4.

' The greatest number of cigar lighter coils are substantially fiat asshown in Fig. 6 which form is fixed by setting the coil in a press orbetween 40 flat dies.

These coils are used in shallow cups it such as shown in Figs. 5 and 6.The outer end of the coil is usually welded to the inner wall of the cupand the inner end of the coil is secured by welding, brazing, riveting,etc. in the central stud ll of the igniter element.

As the wire ribbon isv completely annealed before, the coil is formed,no shifting of the coils' takes place when the device is heated in use.

The coil produced in this way is much more uniform in turns and 'inspacing than those formed in any other known manner.

The use of a cup type receptacle of the general shape indicated on thedrawing is of advantage to in its assistance in holding the coil inposition before the welding operation. As shown in the drawing theradial separation of the convolutions of the finished coil issubstantially uniform and not greater than about twicethe thickness ofthe metal ribbon.

We claim: y

l. The method of making an igniter coil which comprises winding a flatribbon into a helicospiral form with each convolution partiallyoverlapping the preceding convolution in an axial direction and spacedradially therefrom and then pressing and thereby permanently setting allconvolutions in a substantially common plane.

2. The method of forming an igniter coil which compriseswinding a deadsoft ribbon of metal upon an arbor having a helicoidal step, the widthof the step axially of the arbor being less than the width of the ribbonand the height of the step radially'of the arbor axis being greater thanthe thickness of the ribbon and then pressing and thereby permanentlysetting all of the convolutions of the coil into approximately the samegeneral plane. l

3. The method of forming a spiral resistance coil having a plurality ofspaced convolutions, which comprises winding a soft fiat strip ofresistance wire on a stepped conical arbor beginning near the axis andgradually increasing in diameter, each succeeding convolution beingspaced from but partially overlapping the next inner convolution, thenremoving the coil from the arbor and compressing the coil between diesand thereby permanently setting the convolutions into a substantiallycommon plane.

4. The process of making an ignition coil for al, removing the coil fromsaid arbor by relative translation therebetween, shortening the axiallength of said coil by pressure applied in the general direction of the'coil axis.

5. The process of forming a cigar lighter heating coil which compriseswinding substantially flat dead soft electric resistance ribbon on. an

arbor provided with substantially fiat steps of approximately uniformheight and of roughly v not more than abouttwice the thickness of theribbon to form a conical helical coil with the convolutions radiallyspaced, removing the entire coil from the arbor without substantiallyexpanding or contracting the convolutions, by relative translationbetween the arbor and all coni volutions of the coil.

6. The process of forming a generallyspiral heating coil for a cigarlighter which includes winding soft fiat electric resistance. metal intoa conical helical form with the convolutions radially spaced,compressing the coil in the general direction of its axis to verysubstantially shorten the axial length of the coil by pressure appliedto the side edges of the metal until the side edges of the convolutionsand the inner end of the metal are substantially alined from the centerof the coil outwardly.

HENRY W. BILGER. KARL T. KESSEL.

